june 2014 Flashcards
Why is memory management necessary?
organise the use of main memory
… by converting logical addresses to physical addresses
allows programs to sharw/ allocate memory
alliws programs larger than main memory to run
virtual machine
a theoretical computer which privides an environment in which a translator is available
uses an interpreter to run the intermediate code
cir features
holds a binary value
may pass a value to the MAR
mdr features
holds a binary value
may change more than once during a cycle
pc features
holds binary value
always holds only an adress
may change more than once during a cycle
may pass a value to the MAR
lines on a use case diagram
message
circles on a use case diagram
action
parameter passing
parameters passed by value or reference
by value local copy of data is used then discarded
… so value of original data is unchanged
by reference location of data is used
… so changes may be made to value of data
why is low level labguage suitable in the context of a washing machine processor
reflects design of the proccessor
direct access to memory locations
limited memory in processor
direct coding of operations
why is flat file database suitable for use by a family at home
limited amount of data
limited technical ability in family
data format difficult to change
security not a major issue for a family
why is relational datbase suitable for a largw company
software may be available as part of computer package technical help readily available online wasy to add data easy to link other applications large volume of data for company saves space inproves data consistency easy to change data format inproves security
explain the term goal
a problem that needs to be solved
instantiation
setting an initial value to be replaced by a variable
